cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A362238 Expansion of e.g.f.: 1/(1 - x*(1+x)^x).

Original entry on oeis.org

1, 1, 2, 12, 60, 460, 3900, 39438, 456288, 5896224, 85230000, 1349017560, 23353941600, 437432418696, 8828284404576, 190867622500800, 4401749312069760, 107859517575659520, 2798352667710645120, 76636669899079699776, 2209235394261812751360
Offset: 0

Views

Author

Seiichi Manyama, Apr 12 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x*(1+x)^x)))

Formula

a(n) = n! * Sum_{i=0..n} Sum_{j=0..n-i} i^j * Stirling1(n-i-j,j)/(n-i-j)!.

A275277 a(n) = a(n-1) + 3*a(n-2) + 3*a(n-3) + a(n-4), where a(0) = a(1) = a(2) = a(3) = 1.

Original entry on oeis.org

1, 1, 1, 1, 8, 15, 43, 113, 295, 778, 2045, 5377, 14141, 37185, 97784, 257139, 676187, 1778141, 4675903, 12296026, 32334345, 85028273, 223595289, 587979169, 1546184200, 4065935847, 10692021243, 28116360553, 73936416023, 194427497258, 511277848229
Offset: 0

Views

Author

Clark Kimberling, Aug 11 2016

Keywords

Crossrefs

Cf. A099234.

Programs

  • Mathematica
    LinearRecurrence[{1, 3, 3, 1}, {1, 1, 1, 1}, 50]
    RecurrenceTable[{a[0]==a[1]==a[2]==a[3]==1,a[n]==a[n-1]+3a[n-2]+ 3a[n-3]+ a[n-4]},a,{n,30}] (* Harvey P. Dale, Apr 09 2022 *)

Formula

a(n) = a(n-1) + 3*a(n-2) + 3*a(n-3) + a(n-4), where a(0) = a(1) = a(2) = a(3) = 1.
G.f.: (-1 + 3 x^2 + 6 x^3)/(-1 + x + 3 x^2 + 3 x^3 + x^4).

A367284 G.f. satisfies A(x) = 1 + x*A(x) * (1 + x*A(x)^3)^3.

Original entry on oeis.org

1, 1, 4, 19, 107, 648, 4144, 27500, 187654, 1308361, 9280049, 66749995, 485741501, 3569653591, 26454406231, 197482954338, 1483619134872, 11208536870979, 85101381927454, 649017399223259, 4969510058193925, 38189305411228229, 294440263583908772
Offset: 0

Views

Author

Seiichi Manyama, Nov 12 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n, s=3, t=1, u=3) = sum(k=0, n, binomial(t*k+u*(n-k)+1, k)*binomial(s*k, n-k)/(t*k+u*(n-k)+1));

Formula

If g.f. satisfies A(x) = 1 + x*A(x)^t * (1 + x*A(x)^u)^s, then a(n) = Sum_{k=0..n} binomial(t*k+u*(n-k)+1,k) * binomial(s*k,n-k) / (t*k+u*(n-k)+1).
Previous Showing 11-13 of 13 results.